Best available c



BEST AVAILABLE cow 0. c. TRAVER SYNCHRONIZING DEVICE Feb. 8,1927.

2 Sheets-Sheet 1 Orijunal Filed July 29, 1922 Q Oliver C. Tra I T igllBEST AVAILABLE cob Feb. 8. 1927. TRAVER 16549 SYNCHRONIZING DEVICE 2shtssha*.2 L 2 Original Filed July 29, 1922 Fig.5

lnVen -i: or: Oliver C. TT-aVeT';

I-lis J T-thorn e5 Reiuued Feb. 8, 1927, i 5

UNITED STATES s'r AVAILABLE com ISSUED:

PATENT OFFICE.

OLIVER C. 'LBAVER, OI SCH EHEC'I'LDY, NEW YORK, 'ASSIGNOB TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SYHCHBONIZING DEVICE.

Original Ro..1,583,1 20, dated November 24, 1825,

P tot reissue filed December My invention relates to improvements insynchronizing devices and has for an object to provide an improvedsynchronizing de vice for automatically controlling the operation ofconnecting an alternatin current dynamo electric machine to analternating current electric circuit whereby the connection can be madesubstantially only at the inst-ant when the electromotive forces ofthemachine and circuit are alike in frequency, phaseand value. My inventionwill be better understood from the following description taken inconnection with the accompanying drawing, and its scope will be pointedout in the appended claims. s Figure 1 illustrates diagrammatically anembodiment of my invention, and Fi 2 to 11, inclusive, are vector dia111113 57118: trading the rinciples uponwhic "my invention is rorpurposes of illustratioml have shown in 'Fig. 1 anembodinient of myinvention as applied to a three phase alternating current electricsystem comprising an alternating current electric circuit such as a bus1 to which may be connected one or more dynamo electric machines 2 orsources of alternating current in parallel-as is wellknown to the art. Ihave illustrated the dynamo electric machine 2 as an alternator adaptedto be connected to the bus 1 by any suitable circuit controlling means 3arranged to con- ,ftrotn cireuit between the bus 1 and the alter iiator2. The circuit controlling means 3 preferably comprises anelectroresponswe closing means such as a closing coil 5 connected in acontrol circuit 6 which may be.

connected across a control bus 7, and which may include an auxiliaryswitch S m-ranged to be controlled by the circuit controlling means 3 soas to he closed when the {circuit controlling means uis v open and o enwhen the circuit con'tmllinflmeans is closed.

For controlling"thc'control circuit 6, I provide electroiesponsivc meanscomprising a plurality of circuit controlling members 9,110 and 11 whichare arranged to control 7 contacts 12, 13 and 14: or 15, respectively,

ur-runpd in series in the control circuit 6. Th im (Jilin! ty of,diflerentially'eetingjglectronaive means, may comprise Serial No.578,475, filed July 29, 1922 App1icat1on a, 1926; smnm. 158,046.

disk motor type, each element comprising an induction disk and aplurality'of motor elements arranged to exert opposing torques thereon.

' For energizing the motor elements of the formers 19 and 21 areconnectedin circuit for o posing 'electromotive fi forces when their eectromotive forces are in phase and the secondaries of the transformers20 and 22 are connected i'njcircuit 'for' cumulative electromotiveforces when their BIGGHOIHG? tive foroes'are in use -The relay 16 iv ichcontrols'circuitj'controllin member 9 may comprise an induction disk 23,shaded pole motor elements 24 and 25 arranged toexert opposingtorquesthereon, and suitable-means such as a drag magnet -26 for exerting aretarding force onthe disk 23 so as to obtain a time delay action in themovement thereof.

Movement of the disk 23 in jib; direction to member 9 away a fromcircuit closing po'srtionfis limited by any suitable means such asastop- 26" Thej carry circuit controllin position of the stop 26?relatively to the contacts 12 may be determlnedin accordance with theangular movement of the disk 23 necessary to provide the time "delaydesired" and ;in a'practicul embodiment of myinvention I have arrangedthe sto') 26' and the contacts 12 so that the disk 2l may have anangular movement of approximately 180 Motor element 24 is provided'zwithan-energizing winding 27 connected in series relatiori'vvith thesecondaries of the potential transformers 19 end'21 andmotor element 25is provided .with an energizing winding 28 connected 1n seriesrelationwith the sec: ondaries of a the potential transformers 20 and 22.The'motor 'elements'2 tfand 25 tend to exert opposing torques {the disk23 irrespective or the directions of current flow in their windings 27,and 28, respectivel The relay 17 which controls :circuit ion trollingmember 10 may comprise an induc- 'f tion disk 29 and shaded pole'fm'otorelements 've devicesgor relays 16 17 am- 18 h be oftbe shaded poleinduction 3Q; and-"31 arranged to exert opposing BEST AvAiLAeLE COP\torques thereon. Motorelenient 30 is provided with an energizing winding32 connected in series relation with the secondaries of. th transformers19 and 21, and motor element 31 is provided with an energizing winding33 connected in series relation with the secondaries of thetransfoi-uiicrs and. 22. The motor elements 30 and 31 tend to exertopposing torques on the disk 29 irrespective of the directions ofcurrent flow in their windings and 33 respectively. The disk 29 is soshaped and. the shaded poles of the motor elements 30 and 31 so arrangedwith respect to the disk 29 that in the event of either of the motorelements 30, 3]. predominating to turn the disk 29, the torque exertedby the stronger element is increased while the torque exerted by theweaker element is decreased. One way to obtain this effect is'to removea segment of the disk 29 and arrange the shaded poles as shown so thatan increasing area of the disk is presented. adjacent the shaded polefaces of the motor'element tending to exert the greater torque and adecreasing area of the disk adjacent the shadedpole faces of the motorpurpose. of maintaining itself in engagement with its cooperatingcontact. The contacts with the depending portions 40 also act to limitthe movement of the disk 35 in either direction and tend to return thedisk 35 to an intermediate position when the torques exerted by themotor elements 36 and 37 are substantially equal.

For the operation otmysynchronizing device. it will. hc'dcsirable torefer to Figs. :2 to 11, inclusive, which are vector diagrau'isillustrating the principles upon which my invention is based. In thesediagrams, the heavy solid lines designated E and shown in a fixedposition as a reference line, represent the voltage on the bus 1 or avoltage proportional thereto as, for example, the voltage across thesecondary of each of the transformers 19 and '20. The heavy solid linesdesignated 6 represent the voltage of the alternator 2 or a voltageproportional thereto as, for example. thevoltage across the secondary ofeach of the transformers 2i and 29. in accordance with the phaserelation of the two electromotive forces to he vsynchronized.

element tending to exert the smaller torque.-- e heavy dashedii'nesdesignated fl p sent the voltage c reversed The vectors E, r eande assumed equal in length as This construction and arrangement ofparts also provides for a quick positive movement of the disk 29substantially of the nature of a snap action which is desirable.Movementof the disk 29 in a direction to carry circuit controllingmember 10 away from circuit closing position is limited by any suitablemeans such as a stop 34.

The relay 18 which controls circuit controlling member 11 may comprisean induction disk 35 and shaded pole motor elements 36 and 37 arrangedto exert opposing torques thereon. The motor element n6 is provided withan energizing winding 38 connected across the terminals of the secondaryo'l' transformer 21 and the motor element 37 is provided with anenergizing winding 39 connected across the terminals of the secondary ofthe transformer 19. The motor elements 36 and 37 tend to exert opposingtorques on the disk 35 irrespective-of the directions of current flow intheir windings 38 and 39 respectively. Obviously when the motor elements36 and 37 exert equal tor ues, that is to say. when the voltage of the aternator 2 is substantially equal to the voltage on the bus 1, the diskwill tend to remain stationary and the contacts Hand 15 closed.

but uponthe occurrence of a predetermined difference in these voltages,the disk 35 will be turned in one direction or the other toopen eithercontacts 14.01 15." One of the con.1..-icts of ea h of the pairsotcontacts 14L .i2id .15 1'ii;iy be provided with a -depending or tzailportion 40 extending into the path of mmement of the circuit controllingmernber 1i and each of these contact members may also be --s-;ilientlymounted for the this is awondition for controlling the con trol circuit6 under the control of relay element 18 or other equivalent means. Thelight solidllnes designated .a: and yrepresent the vectorial diltereneesof E and e. and E and s. respectively, that is to say, .00 repicsentsthe vcctorial difference and 3/ the rectorial sum of E and e. Thevoltages :r and 3 in accordance with their relative values control theoperation of the relay elements 16 and 17. For convenience, the vectordiagrams are assumed to be divided into four The vector (2 is assumed torotate quadrants a, t), o, andd respectively as indicated in Fig. 10- IFig. 2,1'epnesents the iii-phase condition of the voltages on the'hus 1and the alternator 2. In this case, the vectors E and e,

coincide. w is zero and 7 has its maximum value. N

Fig. 3 represents the voltage of the alternator less than 90 degrees outof phase with the voltage on the bus 1, that is to say volt-v age inquadrant a. In this case, voltage 1/ .is greater thanvoltage m.

Fig. 4 represents the voltage of the alter nator 2, 90 degrees out ofphase with the,

voltage on the bus 1. In this case, volta 71s a? cquals voltage 3/.

nator 2 more than 90 degrees and less than 180 degrees out of phase withthe voltage on the bus 1, that is to say. voltage a in quadrant 6.Inthis case voltage y is lcssithan voltage :12;

Fig. 6 represents the voltage of the ziflti nator 2, 180 degrees outotphase with tl e Fig. '5- represents the voltage of. theallcri sesrAymLAeLE' com 16,540:

the bus 1, that is to say, voltage 0 in quadrant 0. In this case voltage(0 is greater than voltage y.

nator 2, 270. de rccs out of phase with the voltage on the ms 1. In thiscase, voltage :2: equals voltage 3 Fig. 9 represents the voltage of thealter nator 2, more than 270 degrees and less than 360 degrees out ofphase with the voltage on the bus 1, that 1s to say, voltage 6 1nquadrant d aprolchin phase coincidence with voltage E. In the casevoltage 3/ is greater than voltage 0.

Fig. 10 is a summary indicatin the relative values of the voltages at an3 in the diflerent quadrants and under the different 00 ditionsheretofore considered.

rom these figures, particularly Fig. 10, and assuming disk '23 notretarded in its movement and disk 29 circular and motor elements24 and25 and also and 31 to be so alike in features of construction that, whentheir respective windings 27 and 28 and also 32 and 33 are ua lyenergized, equal torques are prod it will be ohserved that through acertain range of phase difference, viz, 90 degrees to 270 degrees orwhen volt-a e y is less than voltage 0:, as in quadrants and c,motor'elements 24 and 30 would predominate to turn their respectiveldisks counter clockwise. that is, the disk 23 to circuit openingposition and the disk 29 to circuit closing sition and that throughanother certain range of hase difference, viz. 270 dcgrcesto 9O cgr'eesor when voltage 1/ is greater than voltage :0, as in quadrants d and a,motor elements 25 and31 would predominate to turn their disks 23 and 29clockwise, that is, disk 23 to circuit closing position and disk 29 tocircuit opcnin posit ion. Under these conditions the dis. s '23 and 29would notsimultaneously be in circuit closing position.

In order that the-circuit controlling means 3 may he closed only whenthe electromotive forces of the bus 1 and alternator 2 are substantiallyalike in phase, frequency and value. I so construct and arrange therelays- 16, 17 and 18 that the movable elements thereof mustsimultaneously he in predeter- ""mmed positions. For tins purpose, I mayconstruct the rcspcclivc motor-elements of relays 16 and 17 oi dillcrcntstrengths and provide means for retarding the movement of the disk 23and also arrange the dislrlZll to provide differential click-ts. Themotor elements 36 and 37 of relay 18 may be sub stantinll v similar inconstruction so as to permit the contacts 14 and 15 to remain Fig. 8represents the voltage of the altergig closed when the difl'erence involtages of the alternator 2 and-bus 1 is "within a predetermined amountwhich in :1 practical embodiment of my invention, 1 have taken so thatthevoltagcs must be within five per cent of each other.

Referring now to Figs. 1 and 1i. motor clement may he so constructed asto predominate over motor element 24 to start disk 23 moving to circuitclosing position when voltagee has reached a. POSli'lOl'l 6 prior tophase, coincidence Where voltage 3; has 9.

Ill

value 1/, and voltzwe m l-lie corresiondin value :0. and contacts 12will be closed with a time delay, and when voltage 6 passes throughphase coincidence to a position 6 where w and 3, again havesubstantially the same values 11: and 3 motor element 2% Willpredominate and more dish 23 to circuit opening position; In a practicalembodiment of my invention voltages fr end y, have substantially thevalues 40 and 220 volts respectively. Thus, as voltage e moves to andaway from phase coincidence through the range of phase diiicrence from 6to e disk 23 will he moved toward. circuit closing position "with ulimcdciav, while in the range of phase difference iron: (2 through phaseopposition to 6 disk 23 will be moved toward circuit opening position,For the values of the voltages :0 and y and the action herein set forth.it will be obvious that motor element 24 should be constructed to exertthe predominant ,torque "when voltage :0 is greater than 40 volts andvoltage 3 less than 220 volts. In which case motor element 25 will exertthe predominant torque whenvoltage or is less than 40 volts andvoltagey' greater than 220 volts. i

The position (2 of tl l c yoltuge e, Fig. 11 corresponds to theplirts inposition as shown in Fig. 1. lo t l 3 position, more of the diskvention, the particular position of a profcrahly, for practical purpo0'', just before phase coincidence as this allows somewhat:

for the time necessary to close the circuit.

controlling means 23, In {1 practical Qnll)()(llinvcntizm; motor clement317s CUHFiI'llCi l (r 22ml roach substantially the values El) and 221)volt; rcerpcctivcly. \Vhcn motor clcn'wnt ll predominates to more thedisk '29 c-hu-lcwic and iucrczlsing area of the disk 2.) will hprescntcdurlinccnt'il's pole flies? and a decreasing urea, adj melt the polefaces lo prcdouainzilc when voltages BES'i AvAtLABLE COP.

(l(i'i'0:l't accordingly in order that motor ele-.

meat 230 may' predominate to move the disk 25) to circuitclosingpositiona. 'In order to in--ure that the disk 29 may'not move tocircuit closing position until after the disk '23 has moved to ciicuitopening position, I construct the motor elements 30 and-31 so that withthe disk 29 in circuit opening position. the voltage (3 must reach aposition a,

such as, for example, substantially quad-- rature orlh) degrees fromphase coincidence where voltages w and 7/ are substantially assumed thatthe voltages of the alternator '2 and bus 1 are equal so that contacts14: and 15 remain closed. If these voltages are not equal one or theother of the contacts 14 and Consequently voltage in will equal, (seeFig. t) before motor element iiO- ran predominate to more the disk 29 tocircuit closing position. tion of e, is immaterial, the main requisiteliving that the position of c where motor ole incnt circuit closingposition should be in phase disp1ace1nent subsequent to theposition e,where motor element 2% predominates to more the disk :33 to circuitopening position. In a practical embodiment of my in- Yentiou, thevalues of the voltages to and ;1 wherein two sources of alternating e1ectromotive force are to be synchronized, a-

correepouding to the position a, of the Yoltage (1. are eachsubstantially 150 volts. \Vh'cn motor elc1'nent'30 predominates .to morethe disk 2'. to circuit closing position, the disk The particular posi-Q0d predominates, to move disk 29 to.

(NW) Fig. 1) will remain substantially in this position until voltage 6reaches the, positiou when motor element ill will again predominate andmore the disk 29 to circuit opening position as heretofore set forth.Thus. as voltage moves to and away from phase coincidence through the.range of phase ditl'crcnce fromc to e,, the disk 29 will lie inrircuitopening position while in the range of phase difference from (2through phase opposition to (7,, the disk 29 Will be in circuit closingpo ition.

It will therefore lie-obvious that the differenro between thefrequencies of the alternator and has voltages must be less than aPl'tt'ltitll'lllj]l((l amount in order that the disk -0 may have time tomore to circuit closing position before disk 29 is moved to circuitopening position. lilorcovc'r, the range ol phase dill'crcnce over whichboth the disk 23 'an'd flll ,may simultaneously he in circuit closingposition is limited and conseqimntl the control rircuitii can becompleted only during a limited number of degreeslrefore synchronism andnot after. This somewhat for the time required to close the circuitcontrolling means 3. It is, of course,

allows 15 will he'opened in consequence of the differential action ofthe motor elements 36, 37 on the disk 35 and therefore the controlair-'- cuit 6 will he held open even thou h the al-.

ternator voltage has thesame reque'ncy as, and is in phase with-the busvoltage. It is therefore clear that the control eircuitfi controllingthe operation of closing the cit cnit controlling means. 3 can he closedonly when the voltages of the alternator 2 and the bus 1 aresubstantially alike' in phase, frequency, and value. It is moreoverclear from Fig. 11 and the explanation therewith.

that contacts 13 which open just before synchronism remain open untildegrees or more after synchronism since motor element 31 of relay 1'?tends to predominate until the voltage-e is substantially 90 degreesbeyond phase coincidcnce.-

Although I have shown and described my invention in considerable detail,I do not wish to be limited to the specific details thereof, as shownand described, but may use such modifications, substitutions orequivalents thereof, as are embraced within the spirit of my invention.v

lVh-at I claim as new and desire to secure by- Letters Patent of theUnited States is: 1.In a system of the class described switch forconnecting the sources, and means for controlling the closing of saidswitch, comprising a plurality of relays connected and arranged so thatthe movable elements of the respective relays must simultaneously he inpredetermined positions to enable said switch to be closed, one of saidrelays being connected to said sources of eleetromo tire 'force andarranged to tend to move to .switch closing position during apredetermined. range of phase diiferencefbetween the 'elec'tromotiveforces near phase co-inieidence and tending to move away from switchclosing position when the phase difference is outside of this range,means for delaying the operation of' said relay whereby it can reachswitch closing position during the predetermined range of, phasedifference only when the frequencies of said clcctromotive' forces are'-substantially 'the same, another of said relay being connoct ed tosaid'sources of electromotiv'e force and arranged to remain in switchclosing position during a range ot' phase difi'erencc beginningsuhsequentlyto the-ending oi said first range of phase difference andending substantially at'phase eta-incidence, and to llo then movequicklyout of switch closing is position, and means connected to saidsources of elcctrorno'tive force and arranged-toper mita an can let a;

BEST AVAILABLE cop the'samevalue. Q g I 2, alternating current electricsysthe electromo'tpve have substantihlly temiwher'ein two sources ofalternating elec" 'tromotiva' tdrce ire to he s; nchronized,'

-' means adaptedto be operated to connect said sources, and means forflectin the operation of said connecting means w en the electromotiveforces of sr sources are in synchronism, comprise -1 a control circuit,a

' plurality of contacts arranged in series in said control circuit and aplurality of relays for controlling said contacts having energizingwindings connected in circuit with said sources to render said rela aresponsive to the phasii relation of sai electromotive -force s, one ofsaid relays bein p ase difierence tween said electromotive cross toclose the contacts controlled there- -0 rative in respznse to apredetermine by and upon the occurrence of a smaller predetermined phasedifference to open and contacts and another of said relays beinoperative in res nse to a predetermin phase diflerencetween saidelectromotive forces with stime delay such that the contacts controlledthereby are moved to circuit closing position while said first contactsare in circuit closing ference between t s frequencies of saidelectromotive force is below a predetermined d 7 v 8. In a system of theclass described wherein two sources of alternating electromotive forceare to be synchronized, a switch for connecting the sources" her andmeans forcontrolling the closing 0% said switch, comprising a luralityofrelays connected and arra so that the movable elements of the respectiverelays must simultaneously be in predetermined positions to enable saidswitch to be closed, twovof said role 5 each having windings connectedto be in ividually responsive to a resultant of theinstantaneous valuesof the electromotive forces to be synchronized, one of the windings oncache-clay being arranged to tend to move theelement of the relayoppositely to the tendency of another winding to move the element sothat movement of the. element of each of said relays depends upon thedifferential effects of thewindings nected so that'wben theelectromotiveforces are in phase one winding approaches its maximum effect and theother winding its minimum effect, one of said relays being arranged totend to close while said electro-'- motive forces are within apredetermined ran of phase difl'erence, means for retar. mg the.operation of said relay so that the element thereof can reach circuitclosing uenciqflf the position only when the electromotive' forces arean the on said member, one'of aaid ition only when the dif- 0 881 eviceacom ber, contacts the other in accordance with there on, the windings oneach relay being conmme, the other relay constructed to remain closedduring a p etermined range of phase ditference whilesaid electromotiveforces are approaching phase coincidence and to move quickly away fromswitch closing position when the electromotive forces, are substantiallyin phase whereby the switch can be closed only when the frequencies ofthe eleetromotive forces are so nearly the same as to permit chronizing(Ii and only-during an interval w e the electromotive forces areapproaching phase coincidence and their base difierence is within apredetermin range. I I

4. In. an alternating current electric sys 0 tom wherein theelectromotive force of an alternating current dynamo electric machine isto be synchronized with the electrbmotiva force an alternating currentelect'riccircuit, synchroni means comp a plurahty of coopera 'ngelectroresponaive devices, one of, said devices comprising a movablemember, contacts" controlled by the movement thereof, and a plurality ofmotor elements arranged to exert oppoamgtorques elements being connected-in circuit to be energised in accordance with the vectorial same! andanother in accordance with the veetorial difierv ence betweensaid-electromotive forces, the construction and tolparts such at said muoperate to move mem tocon o'sing 'timn' n e occurrence of a. difleb'enc'e between sa' elech'omotive andto I move said member hom contactclosing positionj-upon the occurrmce of a smaller pr another mun- WI; 1thereof, means for retarding dia movement of said member, and a pin id'motor elements arranged to exert op 'on'said; I, one .id I conncctedin circuit to be [in accordance with the vectorial sum of and anthediflerence between? said forces whereby movement of'aaid to tact closingposition is elected in dance with the phase difference betwefi v tromotive forces, the construction tend arrangengsnt of. parts bein such thatwhen, the di erencebetween t frequencies of saidel ectromotive forcesexceeds a predator 1Y mined amount said member will tend toreach contactclosing position subsequently to the-movement of said first member fromcontact closing position. I

5 In an alternating current electric system wherein two sources ofalternating elec-' tromotive force are to be synchronized, 1 means forconnecting the sources, and means for controllinggtlwicl of s m scomprises a r d BEST AVAILABLE COP ating electroresponsive devices, eachof said devices comprising a movable member and.

having energizing windings arranged to exbeingconnected in circuit withsaid sources crt opposing effects thereon, the energizing windings ofeach of two of said devices to be energized respectively in accordancewith the sum of and difference between the instantaneousvalues of theelectromotive forces render the devices operative in response t6 thephase relation thereof, the

movable member of one of said two devices being opera ive in response toa predeter-i ;mined phase difference between said elec-- troluotiveforces to move to'circuit closing position and to moveto circuit oeningposition in response to a smaller pre etermined phase difference and theother of said twodevices comprising means for retarding the movement of"the movable member thereof whereby the member is operative in responseto a predetermined phase difference between the electronlotive forces tomove to circuit closing position with a "time delay such that when thedill'erence between the frequencies of said electromotive forces exceedsapredetermined amount circuit closing position is reached subsequentlyto the movement of said first member to circuit opening position, andanother of said plurality of devices having the energizing windingsthereof connected in circuit with said sources to he energized inaccordance with the respective values ofthe electromoti've forces thereot'whereby'the movablememher is moved to circuit opening position uponthe occurrence of a predetermined difference between the electromotiveforces, the construction and arrangement ofpar'ts being such that themovable elements of said pluralityof electroresponsive devices mustsimultaneous-' ly b in predetermined positions, to enable saidconnecting means to be closed.

(5. In an al ernating current electric system wherein two sourcesof'alternatin electromotive force are to be synchronize ,syn! chronizingmeans compris ng a control c1rcnit and aplurality of cooperatingelectroresponsive devices for controlling said cir-. cuit, one of saiddevices comprising arotata ble contact controlling member and, aplurality of motor elements arranged to exert opposing torques thereonconnected in'circuitwith said sources to be, energized in accordancewith the vectorial sum of and difference between the electromotiveforces thereof respectively, the construction and arrangement of partsbeing suchthat upon the occurrence of a predetermined phase differencebetween the electromotive forces said member is quickly moved to,circnit.closing position and upon the occurrence 015B, small er predeterminedphase difireue e is quickly moved to circuit opening positiom i-anotherof devices comprisingja rotatable ccntively movable tact controllingmember, means for retarding the movement thereof and a plurality ofmotor elements arranged to exert opposing torques thereon connected incircuit with said sources to he energized in accordance with thevectorial sum of and. difference between the electromotive forcesthereof respectively, the construction and. arrange ment of parts beingsuch that upon the occurrence of predetermined phase diflerence betweenthe electromotive' forces member is moved to circuit closing positionwith electromotive forces of said sources are substantially equal and insynchromsm, comprising a controlcircuit, a plurality of relacoopcratingcontacts arranged in' series in said control circuit and a plurality ofrelays for controlling said contacts, two of said relayshavingenergizing windings connected in circuit with said sources to rendersaid relays responsive'to the phase relation of the QlGCUOIIIOtlXGforces' thereof, one ofsaid two relays beingoperativeiin response to apredetermined hase difference between the electron'iot-ive orces toclose the contacts controlled. thereby and hold them closed until theoccurrence of a smaller predetermined-phase difference be tween saidelectromotive forces, and another of said two relays being operative inresponse'to a predetermined phase difference between said'electroniotive forces with a time delay such that thecontactscontrolled thereby are moved to circuit "closing position wl'iil'esaidfirst contacts a e in. circuit closing position only when the differencebetween the frequencies of said electrometivefo'rces is below apredetermined value ,and another of said plurality of-relays haw Jugenergiz ng-,w1ndmgs connected;- in; circuit with. said. a creator andsaid circuit re spectivelytorender said relay'operativein response tothedriference between said electromotive force's wherehythe contactscontrolled thereby are moved to circuit opening position upon theoccurrence of a predetermined. difference between said: electromotiveforces,

8511: an alternating current electric systernjwherein two sources ofalternating electroznotive force 7 are to be synchronized, means forconnecting said sources, means REST AVAlLA BLE o oe a i comprising acontrol circuit for effecting the operation of said connecting means,and means for controlling said control'circuit comprising a. pluralityof electroresponsive devices each including a rotatable member,

' contacts controlled thereby and arranged in connected in circuit tofbeenergized in accordance with-the sum 0 the electroniotive forces of saidmachine and said circu1t and the one gizing wind ng of another of saidelements connected in circuit to be energized in accordance with thedifference between said electromotiveforges whereby said devices areresponsive tothe phase 'difierence and difference between thefrequencies of said electromot'ive forces, the rotatable mem' ber of oneof said devices being. adapted upon movement thereof in res use to theoccurrence of a difierence tween the torques exerted thereon by saidmotor elements to increase the efi'ect of the element exerting thegreater torque and decrease the v occurrence of a smaller pr efi'cct ofthe element exerting the smaller torque whereby the predominant motorelementis rendered more effective, the construction and arrangement ofparts being such that said motor elements operate to move said member tocontact controllin "position upon the occurrence of a pre eterminedphase difierence and to hold said member in contact closing ition untilthe ed t ermined phase, difference, and another of said devicescomprising means for retarding the movement of the rotatable memberthereof, the'constructionand arrangement of parts being such that whenthe difierencebetween the frequenciesof said electromotive forces isbelow a predetermined value said rotatable member is caused to-move tocontact closing position while the contacts of said first de-/ vice areclosed whereby said control circuit is completed to effect the closingof said.

. connecting means.

9. In combinatiomtwo alternating current circuits, switching means forconnectin the circuits, and means controlled in accor anoe with thephase relation and the dificrence between the frequenciesof theelectromotive forces of the circuits for starting the closing operationof the switching means only when the phase difference of theelectromotive forces exceeds a predetermined value and the differencebetween the frequencies of the electromotive forces is less tham'lapredeter mined value.

10. In combination, two alternating current circuits, switching meansfor connecting the circuits and-meansconnected to be energized inaccordance with the ditference between the eflects of the sum. of andthe difference between the electromotive forces of the circuits forstarting the closin operation of the switchin means'only wli en thephase difference of the electromotive forces exceeds a predeterminedvalue and the difference between the frequencies of theeletn tromotiveforces is less than a predetermined value. k

11. In combination two alternatin current circuits, means forcontrolling the interconnection of said circuits comprisinga controlcircuit, a relay responsive to condi' tions in said circuits operable toniakeua connection .in the control circuit only during a predeterminedrange of phase difierence between the electromotive forces of thecircuits when the diflerence between the fre-' quencies is less thanapredetermined value and a relay res naive to conditions in saidcircuits operab e within said range to control another connection in thecontrol circuit. a

12. In combination. two alternating current circuits, means forcontrolling the interconnection of said circuitscomprising a controlcircuit, a rela connected and arranged .to be energize in accordancewith the sum of and the diflerence between the electromotive 'forces ofthe circuits operable to make a connection in the control circuit on]durin .a predetermined range of hase di erence tween the electromotive'orces when the frequency difference between the clcctromotivc forcesis-less than aredetermined value, and a rclay connects and arranged tobe'energized 1n accordance with thesum of and the difference betweenthe.

electromotivo forces operable-Within said range to control anotherconnection in the control circuit.

13., In combination, two alternating cur-.

rent circuits, a switch for connecting the circuits, and means forcont-rolli the closing of the switch comprising a p urality of relaysconnected and arranged so that the movable elements thereof mustsimultaneousl v he in predetermined positions to start the closingoperation of the switch, one of said relays being connected to saidcircuits and arranged to tend to move to switch closin position during apredetermined range 0 phase difl'erencehetween the electromotive forcesof the circuits and to move from switch closing position when the phasedifference is. outside this range, means for delaying the operation ofsaid relay whereby the relay can reach switch closing: positioir onlywhen the difference between the freuencies of the electromotive forcesis less t an a predetermined value, and another of said relays beingconnected to said circuits and arranged -to remainin switch closingposition during a rangeof phase dill'erenee BEST AVAILABLE cop beginningsubsequentlyfto the eiidof said iii-st range of phase difference andending prior to phase coincidence and then to .move

quickly-'outof switch closing position. I

14'. In;combiitat ion, .two alternating curqrent circuits, 9. switchiorconnecting the ciredits, and meansfor 'controlli'ngqthe closing oftheswitc'h comprising a, plurality of relays connected and arranged sothat the movable elements thereof must simultaneously be inpredetermined positions to start the. -closing operetion of the switch,one of said relays being connected to said circuitsand arranged to tend-to move tosw itch clos-in '1 position during a'predetermined range-0ihase difference between the electromotive orccs of the circuitsincluding phase coin-' cidence and to move from switch closing positionwhen the phase diit'ei'cnce is outside this range, means for delayingthe operation of and relay whereby the relay-can reach switch closingposition only when the d1flfer= ence between the frequencies ottheelectromotwe forces 18 less than a predetermined value, and'anotherofsaid relays being con.-

nected to said circuits and arranged to remain in switch closingposition during a 'rzinge of phase difference beginning snbse quentlyto" the end of said first range of phaserdifi'erence and ending prior tophase I coincidence and then-to move quickly out of switch closing postion.

15. A synchronizing device comprising a movable circuit controllingmember, means for exerting opposing torques on the member, means forretarding the movement of anzinduction d sk adapted to'be actuated 'inaccordance with the sum of and difference between two electromotiveforces contacts co'ntrollcdby said disks and means for re- .tarding themovement of one of said disks. In witness whereof, I have hereunto setmy hand this 23d day of November, 1926.

' OLIVER. o. TRAVER.

plurality of cooperating relays, eac having the member 'to circuitcontrolling, position,

for exerting opposing

